Analysis Study of Large Diameter Bored Pile Bearing Capacity

Installing bored pile foundations requires a lot of money. This research was conducted to determine the efficiency of using large diameter single piles or small diameter group. The soil data used is soil data for the B Residence Grogol project. For the results of the analysis of the bearing capacity, the highest ultimate bearing capacity is in group piles with 4 piles with a diameter of 100 cm of 3818.75 tons and 4752.81 tons, while for a single pile is a diameter of 400 cm of 7762 .72 tons and 9518.47 tons in borehole 1 and borehole 2 using the ALLPile program. For settlement analysis results, the smallest settlement value is in group piles with 4 piles with a diameter of 100 cm of 3.46 mm and 3.66 mm, while for single pile is a diameter of 400 cm of 2.04 mm and 1.57 mm in borehole 1 and borehole 2 using the ALLPile program. The results of the analysis using the PLAXIS 3D program have the most accurate values because the soil parameters used have been validated with the original soil conditions. Thus, the results of the analysis using the PLAXIS 3D program will be used as a reference in calculating the settlement.


Introduction
The foundation of a building is very important in building construction because the foundation has direct contact with the hard soil beneath it.The foundation serves to bear the weight of the building above it.Thus, the foundation must be calculated correctly so that it can maintain the stability of the building above it against the weight of the building itself, the loads inside the building, external forces such as earthquakes and wind so that unwanted things do not occur.Buildings also must not experience a soil settlement beyond the limits permitted by the government because it can cause damage and danger to buildings.There are two types of foundations, namely shallow foundations and deep foundations.Meanwhile, deep foundations are also divided into two types, namely driven pile foundations and bored pile foundations.This research will discuss more deeply about the Bored Pile foundation.
The Bored Pile Foundation is a foundation built by drilling the soil first, then the drillng hole can be filled with reinforcement and concrete casting is carried out.Bored Pile is usually used on subgrade soils that are very deep and have a large bearing capacity [1].This foundation is usually used when there are many high-rise buildings around the construction area.This is done to prevent cracks in the surrounding buildings due to vibrations caused by pile penetration.Bored piles with large diameters are very effective in transferring and withstanding high loads [2].Bored piles with large diameters are also used to prevent landslides or protect nearby buildings.Large diameter bored pile is becoming a trend and has started to be used in another country [3].For example, in HoChiMinh City for 12 apartment buildings using single piles with diameters of 1.5 meters and 1.8 meters.In addition, quoting from the Avopiling page, the bridge connecting the cities of Auburn and Parramatta also uses a single pile with a diameter of up to 2.7 meters.Contractors say that currently bored piles have reached a diameter of 5 meters according to the Solentache Bachy website [4].This research was conducted to find out whether large diameter bored pile can be more efficient in terms of soil bearing capacity and settlement value compared to small diameter bored pile.
Bearing capacity of Bored Pile is obtained from the bearing capacity of the pile tip and the bearing capacity of the pile cover.The pile end bearing capacity is obtained from the pile tip pressure, while the pile cover capacity is obtained from the frictional bearing strength between the bored pile and the surrounding soil.This Bored Pile can interact with the soil and can produce a bearing capacity that holds and gives strength to the superstructure.In order to produce an accurate bearing capacity, an accurate soil investigation must be carried out.
The B Residence Grogol Apartment Project is a project that uses a large number of Bored Pile foundations.This project uses Bored Pile with a diameter of 1 meter with a total of 187 points and Bored Pile with a diameter of 0.8 meters with a total of 27 points.Bored Pile with this large number will certainly require a considerable amount of money and time.So this research is needed on Bored Pile with a larger diameter to determine its efficiency.This research was conducted using soil investigation data, loading data, and Bored Pile specifications at B Residence Grogol project.
In analyzing the soil bearing capacity and settlement of the Bored Pile foundation of B Residence Grogol project, it will be carried out using PLAXIS 3D software.PLAXIS software is software developed to perform settlement and stability analysis in the geotechnical field.PLAXIS 3D is PLAXIS software with full three-dimensional modeling facilities.
In the construction of the B Residence Grogol project foundation, 187 points of Bored Pile with a diameter of 1 meter were used and 27 points of Bored Pile with a diameter of 0.8 meters.Installing the Bored Pile foundation certainly takes a very long time and costs a lot.
The purpose of this study was to determine the bearing capacity and settlement of small diameter group piles based on soil data at the B Residence Grogol project, to determine the bearing capacity and settlement of large diameter single piles based on soil data on the B Residence Grogol project.

Methodology
The research methodology used is to identify the problem, after identifying the problem we can conduct a literature review.After that, we can collect the data needed in the research.Analysis of superstructure modeling using the ETABS program can be carried out to obtain working load on the column.The next step is calculate bearing capacity and deformation value to validate soil parameters using the ALLPile and PLAXIS 3D programs to find out whether the parameters used are similar to the original soil conditions.After validating the soil parameters, bearing capacity and deformation analysis on small diameter group pile and large diameter single pile foundations can be carried out using the ALLPile and PLAXIS 3D programs.The bearing capacity of a single pile can be determined throught the following formula [5]: The bearing capacity of a pile group will be determined using the following formula: • Converse -Labarre

Working Load on Columns with the ETABS Program
Using ETABS program, the working load on the column then can be determined.

Figure 1 Working Load
Figure 1 shows the maximum load received by the column is 9209.43kN or equivalent to 939 tons.The load to be used in the study is 940 tons.In addition, the maximum moment value on the column in x direction is 880 kNm and the maximum moment value on the column in y direction is -990 kNm.

Soil Modelling in PLAXIS 3D
Based on the parameters obtained from the NSPT data for boreholes 1 and 2, there are 3 types of soil i.e. silty clay, clayey silt and silty sand.Parameters of the soil such as stiffness, strength, and so on were obtained by correlation as shown in Table 1

Bearing Capacity and Settlement Calculation 3.3.1. Bearing Capacity and Settlement Calculation using ALLPile
Table 3 to Table 6 show the results of bearing capacity and settlement calculations using the ALLPile program.7 and Table 8 show the results of settlement calculation using the PLAXIS 3D program.

Comparison of Bearing Capacity and Settlement Calculation
The comparison is carried out by comparing the bearing capacity and settlement in relation with the diameter of piles.For example the 200 cm diameter of large diameter single pile will be compared with group file with configuration 2 x 100 cm, 300 cm diameter of large diameter single pile to group pile with configuration 4 x 75 cm, and so on.-For borehole 1, the bearing capacity of single pile (large diameter) is lower than a group pile (except for diameter 300 cm).Example: o The bearing capacity of 200 cm (large diameter) single pile is lower than group pile of 2 x 100 cm.-For borehole 2, the bearing capacity of single pile (large diameter) is higher than a group pile.Example: o The bearing capacity of 200 cm (large diameter) single pile is higher than group pile of 2 x 100 cm.o The bearing capacity of 300 cm (large diameter) single pile is higher tha group pile of 4 x 75 cm and so on.
Another analysis had been carried out is the settlement analysis, which conducted using manual calculations, the ALLPile program, and the PLAXIS 3D program, with the results as shown in Figure 4 and Figure 5.

Conclusion
Based on the results of the analysis of the bearing capacity of bored piles and land subsidence using the ALLPile and PLAXIS 3D programs, it can be concluded that: The highest ultimate bearing capacity is group pile with 4 piles with a diameter of 100 cm of 3818.75 tons and 4752.81tons in borehole 1 and borehole 2 using the ALLPile program.The smallest settlement value is in group piles with 4 piles with a diameter of 100 cm of 3.46 mm and 3.66 mm in borehole 1 and borehole 2 using the ALLPile program.
Based on the results of the single pile analysis, it can be seen that the larger the diameter of a single pile, the greater the value of its bearing capacity.The highest value of ultimate bearing capacity is single pile with a diameter of 400 cm of 7762.72 tons and 9518.47 tons in borehole 1 and borehole 2 using the ALLPile program.As for the settlement calculation, it can be seen that the larger the diameter of a single pile, the smaller the settlement value will be.The smallest settlement value is in group piles with 4 piles with a diameter of 100 cm by 2.04 mm and 1.57 mm in borehole 1 and borehole 2 using the ALLPile program.

Figure 2 Figure 3
Figure 2 Bearing Capacity of Various Configuration of Piles (Borehole 1)

Figure 2 and
Figure 2 and Figure 3 show the bearing capacity for various dimension or configuration of piles, which shows different results different results, i.e.:-For borehole 1, the bearing capacity of single pile (large diameter) is lower than a group pile (except for diameter 300 cm).Example: o The bearing capacity of 200 cm (large diameter) single pile is lower than group pile of 2 x 100 cm.-For borehole 2, the bearing capacity of single pile (large diameter) is higher than a group pile.Example: o The bearing capacity of 200 cm (large diameter) single pile is higher than group pile of 2 x 100 cm.o The bearing capacity of 300 cm (large diameter) single pile is higher tha group pile of 4 x 75 cm and so on.

Figure 4 Figure 5 Figure 4 and
Figure 4 Pile Settlement for Various Dimension or Configuration (Borehole 1)

Table 2
Soil Parameter at Borehole 2

Table 3
Bearing Capacity Calculation using ALLPile at Borehole 1

Table 4
Bearing Capacity Calculation using ALLPile at Borehole 2

Table 5
Settlement Calculation using ALLPile at Borehole 1